1. Field of the Invention
The present invention relates to a method of producing a substrate for a liquid ejection head used in a liquid ejection head. More particularly, the present invention relates to a method of producing a substrate for an ink jet head used in an ink jet recording head.
2. Description of the Related Art
In recent years, it is desired to etch an inkjet ink supply port with precision and to keep constant the distance between a heater and the ink supply port, thereby improving the performance of the ink jet recording head. For example, Japanese Patent Application Laid-Open No. 2005-35281 discloses a method in which a sacrifice layer is made of aluminum and an ink supply port is formed using an alkaline etchant.
Further, in order to improve the productivity, it is required to reduce the time taken to etch silicon. For example, as disclosed in Japanese Patent Application Laid-Open No. 2009-206335, by the use of an etchant containing an alkaline compound which is a mixture of an organic alkaline compound and an inorganic alkaline compound and containing any one of silicon or a silicon compound, the time taken for anisotropic etching of silicon is attempted to be reduced.
However, depending on the composition of the etchant, the sacrifice layer may be unevenly etched to produce variations in the width of the surface opening of the ink supply port within a wafer surface.
Further, when etching is carried out using the etchant disclosed in Japanese Patent Application Laid-Open No. 2009-206335, as the etching of silicon progresses, the silicon may be eluted in the etchant to reduce the etching rate of aluminum. When etching of silicon further progresses, from a certain region, aluminum may be no longer etched to leave residue of the sacrifice layer. Leaving residue of the sacrifice layer may lower the performance of the ink jet recording head.